In a typical Digital Multiplex Interface (DMX) based LED lighting system, Pulse Width Modulation (PWM) is used to drive the LED's. In a standard PWM system, an intermediate amount of electrical power can be provided by cycling the electrical current between a fully on and a fully off state. The cycling of the current can occur from just a couple of times per minute to well over a thousand times per minute. In all cases, the switching occurs at a high enough rate so as to not interrupt the power supply requirements of the device being powered, in an attempt to limit the visible flickering of the LED's emitted light.
To control the brightness of the LED in a typical DMX based LED lighting system, the duty cycle is adjusted to control the LED on to off time; the duty cycle being defined as the proportion of power on time to the interval of the PWM.
The use of PWM in a DMX based lighting system, while providing a moderately efficient method to control the brightness of an LED, can significantly shorten the lifespan of an LED as the LED is constantly being cycled on and off, typically at a full rated LED current. Each cycling of the power increases the strain of the LED device, shortening the useable lifespan. Furthermore, the constant cycling of power provided to an LED increases the flicker associated with DMX systems, thereby decreasing the aesthetic appeal of an LED lighting system, especially during the video taping or TV broadcasting of the LED.
What is desired, therefore, is a system and method of controlling the brightness of a DMX based LED system that increases the lifespan of the LED's, and decreases the flickering of the LED's